In prior art, a separate linear encoder is known. The separate linear encoder has a scale that is provided with an incremental (INC) track (or an absolute (ABS) track), which constitutes a main track, and a detection head that includes an INC detection portion (or an ABS detecting portion), the detection head being relatively movable with respect to the scale and reads the INC track (or the ABS track). In this type of separate linear encoder, the scale and the detection head are separately provided, and both the scale and the detection head are assembled to chosen machinery or equipment such that they maintain a predetermined mutual positional relationship to each other. A signal strength from the scale is measured by an oscilloscope, and an inclination (yaw angle) of the detection head with respect to the scale (measurement axis direction) that is generated at the time of assembly is adjusted such that the amplitude is at a maximum value (Background Art described in Japanese Patent Application Laid-Open No. 2010-48786).